File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

ACCDB file extension

Access 2007 Database File

Database Files

APK file extension

Android Package File

Executable Files

CAB file extension

Windows Cabinet File

System Files

CSR file extension

Certificate Signing Request File

Web Files

FON file extension

Generic Font File

Font Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MOBI file extension

Mobipocket eBook

eBook Files

MSG file extension

Outlook Mail Message

Text Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SRT file extension

SubRip Subtitle File

Video Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VCD file extension

Virtual CD

Disk Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files